Communication filter for LTE band 41

ABSTRACT

A communication system using a single crystal acoustic resonator device. The device includes a piezoelectric substrate with a piezoelectric layer formed overlying a transfer substrate. A topside metal electrode is formed overlying the substrate. A topside micro-trench is formed within the piezoelectric layer. A topside metal with a topside metal plug is formed within the topside micro-trench. First and second backside cavities are formed within the transfer substrate under the topside metal electrode. A backside metal electrode is formed under the transfer substrate, within the first backside cavity, and under the topside metal electrode. A backside metal plug is formed under the transfer substrate, within the second backside cavity, and under the topside micro-trench. The backside metal plug is connected to the topside metal plug and the backside metal electrode. The topside micro-trench, the topside metal plug, the second backside cavity, and the backside metal plug form a micro-via.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a continuation-in-part application of U.S.patent application Ser. No. 15/647,098, filed Jul. 11, 2017, whichclaims priority to U.S. Pat. App. No. 62/360,904, filed Jul. 11, 2016.

BACKGROUND OF THE INVENTION

The present invention relates generally to electronic devices. Moreparticularly, the present invention provides techniques related to bulkacoustic wave resonator devices, single crystal bulk acoustic waveresonator devices, single crystal filter and resonator devices, and thelike. Merely by way of example, the invention has been applied to asingle crystal resonator device for a communication device, mobiledevice, computing device, among others.

Mobile telecommunication devices have been successfully deployedworld-wide. Over a billion mobile devices, including cell phones andsmartphones, were manufactured in a single year and unit volumecontinues to increase year-over-year. With ramp of 4G/LTE in about 2012,and explosion of mobile data traffic, data rich content is driving thegrowth of the smartphone segment—which is expected to reach 2B per annumwithin the next few years. Coexistence of new and legacy standards andthirst for higher data rate requirements is driving RF complexity insmartphones. Unfortunately, limitations exist with conventional RFtechnology that is problematic, and may lead to drawbacks in the future.

From the above, it is seen that techniques for improving electronicdevices are highly desirable.

BRIEF SUMMARY OF THE INVENTION

The present invention relates generally to electronic devices. Moreparticularly, the present invention provides techniques related to bulkacoustic wave resonator devices, single crystal bulk acoustic waveresonator devices, single crystal filter and resonator devices, and thelike. Merely by way of example, the invention has been applied to asingle crystal resonator device for a communication device, mobiledevice, computing device, among others.

In an example, the present invention provides a communication systemusing a single crystal acoustic resonator device. The device includes apiezoelectric substrate with a piezoelectric layer formed overlying atransfer substrate. In a specific example, the piezoelectric layer isbonded to the transfer substrate using one or more dielectric layerscontaining silicon nitride, silicon oxide, or other adhesion materials.A topside metal electrode is formed overlying the substrate. A topsidemicro-trench is formed within the piezoelectric layer. A topside metalwith a topside metal plug is formed within the topside micro-trench.First and second backside cavities are formed within the transfersubstrate under the topside metal electrode. A backside metal electrodeis formed under the transfer substrate, within the first backsidetrench, and under the topside metal electrode. A backside metal plug isformed under the transfer substrate, within the second backside trench,and under the topside micro-trench. The backside metal plug is connectedto the topside metal plug and the backside metal electrode. The topsidemicro-trench, the topside metal plug, the second backside trench, andthe backside metal plug form a micro-via.

In a specific example, the communication filter can be a bandpass RFfilter characterized by the following: 50Ω input/output, no externalmatching requirement, low insertion loss, high interference rejection,−20° C. to +85° C. operation, +31 dBm absolute max input power, 2.0×1.6mm footprint, 0.90 mm max height, RoHS 6 compliant, halogen free, andTetrabromobisphenal A (TBBPA) free. This filter can be used insmartphones, tablets, Internet of things (IoT), and other mobile orportable communication devices. Those of ordinary skill in the art willrecognize other variations, modifications, and alternatives.

One or more benefits are achieved over pre-existing techniques using theinvention. In particular, the present device can be manufactured in arelatively simple and cost effective manner while using conventionalmaterials and/or methods according to one of ordinary skill in the art.Using the present method, one can create a reliable single crystal basedacoustic filter or resonator using multiple ways of three-dimensionalstacking through a wafer level process. Such single crystal acousticresonators enable high bandwidth-low loss filters in a miniature formfactor, and such filters or resonators can be implemented in an RFfilter device, an RF filter system, or the like. In an example, thiscommunication filter can be a miniature filter configured for use in a2496-2690 MHz wireless frequency spectrum. This filter can operateconcurrently with adjacent 2.4 GHz bands including Wi-Fi, WLAN,Bluetooth, ISM, and the like. Depending upon the embodiment, one or moreof these benefits may be achieved.

A further understanding of the nature and advantages of the inventionmay be realized by reference to the latter portions of the specificationand attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more fully understand the present invention, reference ismade to the accompanying drawings. Understanding that these drawings arenot to be considered limitations in the scope of the invention, thepresently described embodiments and the presently understood best modeof the invention are described with additional detail through use of theaccompanying drawings in which:

FIG. 1A is a simplified diagram illustrating an acoustic resonatordevice having topside interconnections according to an example of thepresent invention.

FIG. 1B is a simplified diagram illustrating an acoustic resonatordevice having bottom-side interconnections according to an example ofthe present invention.

FIG. 1C is a simplified diagram illustrating an acoustic resonatordevice having interposer/cap-free structure interconnections accordingto an example of the present invention.

FIG. 1D is a simplified diagram illustrating an acoustic resonatordevice having interposer/cap-free structure interconnections with ashared backside trench according to an example of the present invention.

FIGS. 2 and 3 are simplified diagrams illustrating steps for a method ofmanufacture for an acoustic resonator device according to an example ofthe present invention.

FIG. 4A is a simplified diagram illustrating a step for a methodcreating a topside micro-trench according to an example of the presentinvention.

FIGS. 4B and 4C are simplified diagrams illustrating alternative methodsfor conducting the method step of forming a topside micro-trench asdescribed in FIG. 4A.

FIGS. 4D and 4E are simplified diagrams illustrating an alternativemethod for conducting the method step of forming a topside micro-trenchas described in FIG. 4A.

FIGS. 5 to 8 are simplified diagrams illustrating steps for a method ofmanufacture for an acoustic resonator device according to an example ofthe present invention.

FIG. 9A is a simplified diagram illustrating a method step for formingbackside cavities according to an example of the present invention.

FIGS. 9B and 9C are simplified diagrams illustrating an alternativemethod for conducting the method step of forming backside cavities, asdescribed in FIG. 9A, and simultaneously singulating a transfersubstrate according to an example of the present invention.

FIG. 10 is a simplified diagram illustrating a method step formingbackside metallization and electrical interconnections between top andbottom sides of a resonator according to an example of the presentinvention.

FIGS. 11A and 11B are simplified diagrams illustrating alternative stepsfor a method of manufacture for an acoustic resonator device accordingto an example of the present invention.

FIGS. 12A to 12E are simplified diagrams illustrating steps for a methodof manufacture for an acoustic resonator device using a blind viastructure according to an example of the present invention.

FIG. 13 is a simplified diagram illustrating a step for a method ofmanufacture for an acoustic resonator device according to an example ofthe present invention.

FIGS. 14A to 14G are simplified diagrams illustrating method steps for acap wafer process for an acoustic resonator device according to anexample of the present invention.

FIGS. 15A-15E are simplified diagrams illustrating method steps formaking an acoustic resonator device with shared backside trench, whichcan be implemented in both interposer/cap and interposer free versions,according to examples of the present invention.

FIG. 16 is a simplified block diagram illustrating a communicationssystem using an one or more communication filter devices according to anexample of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates generally to electronic devices. Moreparticularly, the present invention provides techniques related to bulkacoustic wave resonator devices, single crystal bulk acoustic waveresonator devices, single crystal filter and resonator devices, and thelike. Merely by way of example, the invention has been applied to asingle crystal resonator device for a communication device, mobiledevice, computing device, among others.

FIG. 1A is a simplified diagram illustrating an acoustic resonatordevice 101 having topside interconnections according to an example ofthe present invention. As shown, device 101 includes a transfersubstrate 112 with an overlying single crystal piezoelectric layer 120,which has a micro-via 129. In a specific example, the piezoelectriclayer is bonded to the transfer substrate using one or more dielectriclayers containing silicon nitride, silicon oxide, or other adhesionmaterials. The micro-via 129 can include a topside micro-trench 121, atopside metal plug 146, a backside trench 114, and a backside metal plug147. Although device 101 is depicted with a single micro-via 129, device101 may have multiple micro-vias. A topside metal electrode 130 isformed overlying the piezoelectric layer 120. A top cap structure isbonded to the piezoelectric layer 120. This top cap structure includesan interposer substrate 119 with one or more through-vias 151 that areconnected to one or more top bond pads 143, one or more bond pads 144,and topside metal 145 with topside metal plug 146. Solder balls 170 areelectrically coupled to the one or more top bond pads 143.

The thinned substrate 112 has the first and second backside cavities113, 114. A backside metal electrode 131 is formed underlying a portionof the transfer substrate 112, the first backside trench 113, and thetopside metal electrode 130. The backside metal plug 147 is formedunderlying a portion of the transfer substrate 112, the second backsidetrench 114, and the topside metal 145. This backside metal plug 147 iselectrically coupled to the topside metal plug 146 and the backsidemetal electrode 131. A backside cap structure 161 is bonded to thetransfer substrate 112, underlying the first and second backsidecavities 113, 114. Further details relating to the method of manufactureof this device will be discussed starting from FIG. 2.

FIG. 1B is a simplified diagram illustrating an acoustic resonatordevice 102 having backside interconnections according to an example ofthe present invention. As shown, device 101 includes a transfersubstrate 112 with an overlying piezoelectric layer 120, which has amicro-via 129. The micro-via 129 can include a topside micro-trench 121,a topside metal plug 146, a backside trench 114, and a backside metalplug 147. Although device 102 is depicted with a single micro-via 129,device 102 may have multiple micro-vias. A topside metal electrode 130is formed overlying the piezoelectric layer 120. A top cap structure isbonded to the piezoelectric layer 120. This top cap structure 119includes bond pads which are connected to one or more bond pads 144 andtopside metal 145 on piezoelectric layer 120. The topside metal 145includes a topside metal plug 146.

The thinned substrate 112 has the first and second backside cavities113, 114. A backside metal electrode 131 is formed underlying a portionof the transfer substrate 112, the first backside trench 113, and thetopside metal electrode 130. A backside metal plug 147 is formedunderlying a portion of the transfer substrate 112, the second backsidetrench 114, and the topside metal plug 146. This backside metal plug 147is electrically coupled to the topside metal plug 146. A backside capstructure 162 is bonded to the transfer substrate 112, underlying thefirst and second backside cavities. One or more backside bond pads (171,172, 173) are formed within one or more portions of the backside capstructure 162. Solder balls 170 are electrically coupled to the one ormore backside bond pads 171-173. Further details relating to the methodof manufacture of this device will be discussed starting from FIG. 14A.

FIG. 1C is a simplified diagram illustrating an acoustic resonatordevice having interposer/cap-free structure interconnections accordingto an example of the present invention. As shown, device 103 includes atransfer substrate 112 with an overlying single crystal piezoelectriclayer 120, which has a micro-via 129. The micro-via 129 can include atopside micro-trench 121, a topside metal plug 146, a backside trench114, and a backside metal plug 147. Although device 103 is depicted witha single micro-via 129, device 103 may have multiple micro-vias. Atopside metal electrode 130 is formed overlying the piezoelectric layer120. The thinned substrate 112 has the first and second backsidecavities 113, 114. A backside metal electrode 131 is formed underlying aportion of the transfer substrate 112, the first backside trench 113,and the topside metal electrode 130. A backside metal plug 147 is formedunderlying a portion of the transfer substrate 112, the second backsidetrench 114, and the topside metal 145. This backside metal plug 147 iselectrically coupled to the topside metal plug 146 and the backsidemetal electrode 131. Further details relating to the method ofmanufacture of this device will be discussed starting from FIG. 2.

FIG. 1D is a simplified diagram illustrating an acoustic resonatordevice having interposer/cap-free structure interconnections with ashared backside trench according to an example of the present invention.As shown, device 104 includes a transfer substrate 112 with an overlyingsingle crystal piezoelectric layer 120, which has a micro-via 129. Themicro-via 129 can include a topside micro-trench 121, a topside metalplug 146, and a backside metal 147. Although device 104 is depicted witha single micro-via 129, device 104 may have multiple micro-vias. Atopside metal electrode 130 is formed overlying the piezoelectric layer120. The thinned substrate 112 has a first backside trench 113. Abackside metal electrode 131 is formed underlying a portion of thetransfer substrate 112, the first backside trench 113, and the topsidemetal electrode 130. A backside metal 147 is formed underlying a portionof the transfer substrate 112, the second backside trench 114, and thetopside metal 145. This backside metal 147 is electrically coupled tothe topside metal plug 146 and the backside metal electrode 131. Furtherdetails relating to the method of manufacture of this device will bediscussed starting from FIG. 2.

FIGS. 2 and 3 are simplified diagrams illustrating steps for a method ofmanufacture for an acoustic resonator device according to an example ofthe present invention. This method illustrates the process forfabricating an acoustic resonator device similar to that shown in FIG.1A. FIG. 2 can represent a method step of providing a partiallyprocessed piezoelectric substrate. As shown, device 102 includes atransfer substrate 110 with a piezoelectric layer 120 formed overlying.In a specific example, the transfer substrate can include silicon,silicon carbide, aluminum oxide, silicon-on-insulation (SOI), or singlecrystal aluminum gallium nitride materials, or the like. Thepiezoelectric layer 120 can include a piezoelectric single crystal layeror a thin film piezoelectric single crystal layer.

FIG. 3 can represent a method step of forming a top side metallizationor top resonator metal electrode 130. In a specific example, the topsidemetal electrode 130 can include a molybdenum, aluminum, ruthenium, ortitanium material, or the like and combinations thereof. This layer canbe deposited and patterned on top of the piezoelectric layer by alift-off process, a wet etching process, a dry etching process, a metalprinting process, a metal laminating process, or the like. The lift-offprocess can include a sequential process of lithographic patterning,metal deposition, and lift-off steps to produce the topside metal layer.The wet/dry etching processes can includes sequential processes of metaldeposition, lithographic patterning, metal deposition, and metal etchingsteps to produce the topside metal layer. Those of ordinary skill in theart will recognize other variations, modifications, and alternatives.

In an example, the method can further include forming a dielectric layeroverlying the top metal electrode 130 and the piezoelectric layer 120.This layer can include Silicon Nitride (SiN), Silicon Dioxide (SiO₂), orthe like. In a specific example, the dielectric layer may include astack of SiN and SiO₂ layers or a combination of other types ofdielectric layers. Prior to the steps of FIGS. 5-8, “vias” may be openedup to provide a path for other interconnect metals or electrodes toconnect to the top metal electrode 130. This process may also be appliedto other interconnect metals and electrodes implemented on the bottomside of the acoustic resonator device as well.

FIG. 4A is a simplified diagram illustrating a step for a method ofmanufacture for an acoustic resonator device 401 according to an exampleof the present invention. This figure can represent a method step offorming one or more topside micro-trenches 121 within a portion of thepiezoelectric layer 120. This topside micro-trench 121 can serve as themain interconnect junction between the top and bottom sides of theacoustic membrane, which will be developed in later method steps. In anexample, the topside micro-trench 121 is extends all the way through thepiezoelectric layer 120 and stops in the transfer substrate 110. Thistopside micro-trench 121 can be formed through a dry etching process, alaser drilling process, or the like. FIGS. 4B and 4C describe theseoptions in more detail.

FIGS. 4B and 4C are simplified diagrams illustrating alternative methodsfor conducting the method step as described in FIG. 4A. As shown, FIG.4B represents a method step of using a laser drill, which can quicklyand accurately form the topside micro-trench 121 in the piezoelectriclayer 120. In an example, the laser drill can be used to form nominal 50um holes, or holes between 10 um and 500 um in diameter, through thepiezoelectric layer 120 and stop in the transfer substrate 110 below theinterface between layers 120 and 110. A protective layer 122 can beformed overlying the piezoelectric layer 120 and the topside metalelectrode 130. This protective layer 122 can serve to protect the devicefrom laser debris and to provide a mask for the etching of the topsidemicro-via 121. In a specific example, the laser drill can be an 11W highpower diode-pumped UV laser, or the like. This mask 122 can besubsequently removed before proceeding to other steps. The mask may alsobe omitted from the laser drilling process, and air flow can be used toremove laser debris.

FIG. 4C can represent a method step of using a dry etching process toform the topside micro-trench 121 in the piezoelectric layer 120. Asshown, a lithographic masking layer 123 can be forming overlying thepiezoelectric layer 120 and the topside metal electrode 130. The topsidemicro-trench 121 can be formed by exposure to plasma, or the like.

FIGS. 4D and 4E are simplified diagrams illustrating an alternativemethod for conducting the method step as described in FIG. 4A. Thesefigures can represent the method step of manufacturing multiple acousticresonator devices simultaneously. In FIG. 4D, two devices are shown onDie #1 and Die #2, respectively. FIG. 4E shows the process of forming amicro-via 121 on each of these dies while also etching a scribe line 124or dicing line. In an example, the etching of the scribe line 124singulates and relieves stress in the piezoelectric single crystal layer120.

FIGS. 5 to 8 are simplified diagrams illustrating steps for a method ofmanufacture for an acoustic resonator device according to an example ofthe present invention. FIG. 5 can represent the method step of formingone or more bond pads 140 and forming a topside metal 141 electricallycoupled to at least one of the bond pads 140. The topside metal 141 caninclude a topside metal plug 146 formed within the topside micro-trench121. In a specific example, the topside metal plug 146 fills the topsidemicro-trench 121 to form a topside portion of a micro-via.

In an example, the bond pads 140 and the topside metal 141 can include agold, aluminum, copper, or other interconnect metal material dependingupon the application of the device. These metal materials can be formedby a lift-off process, a wet etching process, a dry etching process, ascreen-printing process, an electroplating process, a metal printingprocess, or the like. In a specific example, the deposited metalmaterials can also serve as bond pads for a cap structure, which will bedescribed below.

In an example, the method can further include forming a dielectric layeroverlying the top metal electrode 130, the bond pad 140, the topsidemetal 141, the topside metal plug 146, and the piezoelectric layer 120.This layer may service as a passivation/protection layer and can includeSilicon Nitride (SiN), Silicon Dioxide (SiO₂), or the like. In aspecific example, the dielectric layer may include a stack of SiN andSiO₂ layers or a combination of other types of dielectric layers.Similar to before, “vias” may be opened up to provide a path for otherinterconnect metals or electrodes to connect to any of theabove-mentioned interconnect metals, electrodes, or bond pads. Thisprocess may also be applied to other interconnect metals, electrodes,and bond pads on the bottom side of the acoustic resonator device aswell.

FIG. 6 can represent a method step for preparing the acoustic resonatordevice for bonding, which can be a hermetic bonding. As shown, a top capstructure is positioned above the partially processed acoustic resonatordevice as described in the previous figures. The top cap structure canbe formed using an interposer substrate 119 in two configurations: fullyprocessed interposer version 601 (through glass via) and partiallyprocessed interposer version 602 (blind via version). In the 601version, the interposer substrate 119 includes through-via structures151 that extend through the interposer substrate 119 and areelectrically coupled to bottom bond pads 142 and top bond pads 143. Inthe 602 version, the interposer substrate 119 includes blind viastructures 152 that only extend through a portion of the interposersubstrate 119 from the bottom side. These blind via structures 152 arealso electrically coupled to bottom bond pads 142.

According to various examples, the top cap structure can include asilicon substrate, a sapphire (Al₂O₃) substrate, glass, smart-glass, ametallized laminate substrate, or other like material. An example with atop cap structure using an interposer substrate can include a glassmaterial with one or more thru metal via structures. A silicon top capstructure can have one or more thru silicon via (TSV) structures.Further, a top cap structure can include a metallized laminate substratewith one or more thru substrate via structures. Those of ordinary skillin the art will recognize other variations, modifications, andalternatives.

FIG. 7 can represent a method step of bonding the top cap structure tothe partially processed acoustic resonator device. As shown, thesubstrate 119 is bonded to the piezoelectric layer by the bond pads(140, 142) and the topside metal 141, which are now denoted as bond pad144 and topside metal 145. This bonding process can be done using acompression bond method or the like. FIG. 8 can represent a method stepof thinning the transfer substrate 110, which is now denoted as transfersubstrate 111. This substrate thinning process can include grinding andetching processes or the like. In a specific example, this process caninclude a wafer backgrinding process followed by stress removal, whichcan involve dry etching, CMP polishing, or annealing processes.

FIG. 9A is a simplified diagram illustrating a step for a method ofmanufacture for an acoustic resonator device 901 according to an exampleof the present invention. FIG. 9A can represent a method step forforming backside cavities 113 and 114 to allow access to thepiezoelectric layer from the backside of the transfer substrate 111. Inan example, the first backside cavity 113 can be formed within thetransfer substrate 111 and underlying the topside metal electrode 130.The second backside cavity 114 can be formed within the transfersubstrate 111 and underlying the topside micro-trench 121 and topsidemetal plug 146. This substrate is now denoted thinned substrate 112. Ina specific example, these cavities 113 and 114 can be formed using deepreactive ion etching (DRIE) processes, Bosch processes, or the like. Thesize, shape, and number of the cavities may vary with the design of theacoustic resonator device. In various examples, the first backsidecavity may be formed with a trench shape similar to a shape of thetopside metal electrode or a shape of the backside metal electrode. Thefirst backside cavity may also be formed with a trench shape that isdifferent from both a shape of the topside metal electrode and thebackside metal electrode.

FIGS. 9B and 9C are simplified diagrams illustrating an alternativemethod for conducting the method step as described in FIG. 9A. LikeFIGS. 4D and 4E, these figures can represent the method step ofmanufacturing multiple acoustic resonator devices simultaneously. InFIG. 9B, two devices with cap structures are shown on Die #1 and Die #2,respectively. FIG. 9C shows the process of forming backside cavities(113, 114) on each of these dies while also etching a scribe line 115 ordicing line. In an example, the etching of the scribe line 115 providesan optional way to singulate the backside wafer 112.

FIG. 10 is a simplified diagram illustrating a step for a method ofmanufacture for an acoustic resonator device 1000 according to anexample of the present invention. This figure can represent a methodstep of forming a backside metal electrode 131 and a backside metal plug147 within the backside cavities of the transfer substrate 112. In anexample, the backside metal electrode 131 can be formed underlying oneor more portions of the thinned substrate 112, within the first backsidecavity 113, and underlying the topside metal electrode 130. This processcompletes the resonator structure within the acoustic resonator device.The backside metal plug 147 can be formed underlying one or moreportions of the thinned substrate 112, within the second backside cavity114, and underlying the topside micro-trench 121. The backside metalplug 147 can be electrically coupled to the topside metal plug 146 andthe backside metal electrode 131. In a specific example, the backsidemetal electrode 130 can include a molybdenum, aluminum, ruthenium, ortitanium material, or the like and combinations thereof. The backsidemetal plug can include a gold material, low resistivity interconnectmetals, electrode metals, or the like. These layers can be depositedusing the deposition methods described previously.

FIGS. 11A and 11B are simplified diagrams illustrating alternative stepsfor a method of manufacture for an acoustic resonator device accordingto an example of the present invention. These figures show methods ofbonding a backside cap structure underlying the transfer substrate 112.In FIG. 11A, the backside cap structure is a dry film cap 161, which caninclude a permanent photo-imagable dry film such as a solder mask,polyimide, or the like. Bonding this cap structure can be cost-effectiveand reliable, but may not produce a hermetic seal. In FIG. 11B, thebackside cap structure is a substrate 162, which can include a silicon,glass, or other like material. Bonding this substrate can provide ahermetic seal, but may cost more and require additional processes.Depending upon application, either of these backside cap structures canbe bonded underlying the first and second backside vias.

FIGS. 12A to 12E are simplified diagrams illustrating steps for a methodof manufacture for an acoustic resonator device according to an exampleof the present invention. More specifically, these figures describeadditional steps for processing the blind via interposer “602” versionof the top cap structure or other similar top cap structure versions,such as a silicon top cap, a metallized laminate top cap, and others.FIG. 12A shows an acoustic resonator device 1201 with blind vias 152 inthe top cap structure. In FIG. 12B, the interposer substrate 119 isthinned, which forms a thinned interposer substrate 118, to expose theblind vias 152. This thinning process can be a combination of a grindingprocess and etching process as described for the thinning of thetransfer substrate. In FIG. 12C, a redistribution layer (RDL) processand metallization process can be applied to create top cap bond pads 160that are formed overlying the blind vias 152 and are electricallycoupled to the blind vias 152. As shown in FIG. 12D, a ball grid array(BGA) process can be applied to form solder balls 170 overlying andelectrically coupled to the top cap bond pads 160. This process leavesthe acoustic resonator device ready for wire bonding 171, as shown inFIG. 12E.

FIG. 13 is a simplified diagram illustrating a step for a method ofmanufacture for an acoustic resonator device according to an example ofthe present invention. As shown, device 1300 includes two fullyprocessed acoustic resonator devices that are ready to singulation tocreate separate devices. In an example, the die singulation process canbe done using a wafer dicing saw process, a laser cut singulationprocess, or other processes and combinations thereof.

FIGS. 14A to 14G are simplified diagrams illustrating steps for a methodof manufacture for an acoustic resonator device according to an exampleof the present invention. This method illustrates the process forfabricating an acoustic resonator device similar to that shown in FIG.1B. The method for this example of an acoustic resonator can go throughsimilar steps as described in FIGS. 1-5. FIG. 14A shows where thismethod differs from that described previously. Here, the top capstructure substrate 119 and only includes one layer of metallizationwith one or more bottom bond pads 142. Compared to FIG. 6, there are novia structures in the top cap structure because the interconnectionswill be formed on the bottom side of the acoustic resonator device.

FIGS. 14B to 14F depict method steps similar to those described in thefirst process flow. FIG. 14B can represent a method step of bonding thetop cap structure to the piezoelectric layer 120 through the bond pads(140, 142) and the topside metal 141, now denoted as bond pads 144 andtopside metal 145 with topside metal plug 146. FIG. 14C can represent amethod step of thinning the transfer substrate 110, which forms atransfer substrate 111, similar to that described in FIG. 8. FIG. 14Dcan represent a method step of forming first and second backsidecavities, similar to that described in FIG. 9A. FIG. 14E can represent amethod step of forming a backside metal electrode 131 and a backsidemetal plug 147, similar to that described in FIG. 10. FIG. 14F canrepresent a method step of bonding a backside cap structure 162, similarto that described in FIGS. 11A and 11B.

FIG. 14G shows another step that differs from the previously describedprocess flow. Here, the backside bond pads 171, 172, and 173 are formedwithin the backside cap structure 162. In an example, these backsidebond pads 171-173 can be formed through a masking, etching, and metaldeposition processes similar to those used to form the other metalmaterials. A BGA process can be applied to form solder balls 170 incontact with these backside bond pads 171-173, which prepares theacoustic resonator device 1407 for wire bonding.

FIGS. 15A to 15E are simplified diagrams illustrating steps for a methodof manufacture for an acoustic resonator device according to an exampleof the present invention. This method illustrates the process forfabricating an acoustic resonator device similar to that shown in FIG.1B. The method for this example can go through similar steps asdescribed in FIG. 1-5. FIG. 15A shows where this method differs fromthat described previously. A temporary carrier 218 with a layer oftemporary adhesive 217 is attached to the substrate. In a specificexample, the temporary carrier 218 can include a glass wafer, a siliconwafer, or other wafer and the like.

FIGS. 15B to 15F depict method steps similar to those described in thefirst process flow. FIG. 15B can represent a method step of thinning thetransfer substrate 110, which forms a thinned substrate 111, similar tothat described in FIG. 8. In a specific example, the thinning of thetransfer substrate 110 can include a back side grinding process followedby a stress removal process. The stress removal process can include adry etch, a Chemical Mechanical Planarization (CMP), and annealingprocesses.

FIG. 15C can represent a method step of forming a shared backside cavity113, similar to the techniques described in FIG. 9A. The main differenceis that the shared backside cavity is configured underlying both topsidemetal electrode 130, topside micro-trench 121, and topside metal plug146. In an example, the shared backside cavity 113 is a backsideresonator cavity that can vary in size, shape (all possible geometricshapes), and side wall profile (tapered convex, tapered concave, orright angle). In a specific example, the forming of the shared backsidecavity 113 can include a litho-etch process, which can include aback-to-front alignment and dry etch of the backside substrate 111. Thepiezoelectric layer 120 can serve as an etch stop layer for the formingof the shared backside cavity 113.

FIG. 15D can represent a method step of forming a backside metalelectrode 131 and a backside metal 147, similar to that described inFIG. 10. In an example, the forming of the backside metal electrode 131can include a deposition and patterning of metal materials within theshared backside cavity 113. Here, the backside metal 131 serves as anelectrode and the backside plug/connect metal 147 within the micro-via121. The thickness, shape, and type of metal can vary as a function ofthe resonator/filter design. As an example, the backside electrode 131and via plug metal 147 can be different metals. In a specific example,these backside metals 131, 147 can either be deposited and patterned onthe surface of the piezoelectric layer 120 or rerouted to the backsideof the substrate 112. In an example, the backside metal electrode may bepatterned such that it is configured within the boundaries of the sharedbackside cavity such that the backside metal electrode does not come incontact with one or more side-walls of the transfer substrate createdduring the forming of the shared backside cavity.

FIG. 15E can represent a method step of bonding a backside cap structure162, similar to that described in FIGS. 11A and 11B, following ade-bonding of the temporary carrier 218 and cleaning of the topside ofthe device to remove the temporary adhesive 217. Those of ordinary skillin the art will recognize other variations, modifications, andalternatives of the methods steps described previously.

According to an example, the present invention includes a method forforming a piezoelectric layer to fabricate an acoustic resonator device.More specifically, the present method includes forming a single crystalmaterial to be used to fabricate the acoustic resonator device. Bymodifying the strain state of the III-Nitride (III-N) crystal lattice,the present method can change the piezoelectric properties of the singlecrystal material to adjust the acoustic properties of subsequent devicesfabricated from this material. In a specific example, the method forforming the strained single crystal material can include modification ofgrowth conditions of individual layers by employing one or a combinationof the following parameters; gas phase reactant ratios, growth pressure,growth temperature, and introduction of impurities.

In an example, the single crystal material is grown epitaxially upon asubstrate. Methods for growing the single crystal material can includemetal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy(MBE), hydride vapor phase epitaxy (HVPE), atomic layer deposition(ALD), or the like. Various process conditions can be selectively variedto change the piezoelectric properties of the single crystal material.These process conditions can include temperature, pressure, layerthickness, gas phase ratios, and the like. For example, the temperatureconditions for films containing aluminum (Al) and gallium (Ga) and theiralloys can range from about 800 to about 1500 degrees Celsius. Thetemperature conditions for films containing Al, Ga, and indium (In) andtheir alloys can range from about 600 to about 1000 degrees Celsius. Inanother example, the pressure conditions for films containing Al, Ga,and In and their alloys can range from about 1E-4 Torr to about 900Torr.

FIG. 16 is a simplified block diagram illustrating a communicationssystem using an one or more communication filter devices according to anexample of the present invention. As shown, communications system 1600includes an antenna 1610 connected is series to a switch bank 1620 andfilter (or bank of filters) 1630. This filter 1630 is connected to apair of switches (or switch banks) 1641, 1642. The first switch 1641 isconnected to a power amplifier (or bank of PA's) 1650, while the secondswitch 1642 is connected to a low noise amplifier (or bank or LNA's)1660. This system 1600 is configured for both transmit and receivepaths.

In a communications system, filters are required in both the transmitand receive paths. However, these paths can be implemented separately ortogether, i.e., a transceiver chip. Depending on the complexity of thesystem architecture, switches or banks of switches can be used tocontrol the signal flow through different paths both in and out.Generally, any of the filters 1630 that is electrically connected to theantenna 1610 and a PA 1650 is configured for the transmit side, whileany of the filters 1630 that is electrically connected to the antenna1610 and an LNA 1660 is configured for the receive side. The number offilters and switches can vary depending on the number of bands supportedand other tradeoffs. Those of ordinary skill in the art will recognizeother variations, modifications, and alternatives.

In an example, the duplexers and filters module 1620 can include one ormore single crystal acoustic resonators devices. Each of these devicecan include a piezoelectric substrate with a piezoelectric layer formedoverlying a transfer substrate. A topside metal electrode is formedoverlying the substrate. A topside micro-trench is formed within thepiezoelectric layer. A topside metal with a topside metal plug is formedwithin the topside micro-trench. First and second backside cavities areformed within the transfer substrate under the topside metal electrode.A backside metal electrode is formed under the transfer substrate,within the first backside cavity, and under the topside metal electrode.A backside metal plug is formed under the transfer substrate, within thesecond backside cavity, and under the topside micro-trench. The backsidemetal plug is connected to the topside metal plug and the backside metalelectrode. The topside micro-trench, the topside metal plug, the secondbackside cavity, and the backside metal plug form a micro-via.

In a specific example, the communication filter can be a bandpass RFfilter characterized by the following: 50Ω input/output, no externalmatching requirement, low insertion loss, high interference rejection,−20° C. to +85° C. operation, +31 dBm absolute max input power, 2.0×1.6mm footprint, 0.90 mm max height, RoHS 6 compliant, halogen free, andTetrabromobisphenal A (TBBPA) free. This filter can be used insmartphones, tablets, Internet of things (IoT), and other mobile orportable communication devices. Those of ordinary skill in the art willrecognize other variations, modifications, and alternatives.

The following table provides the electrical specifications for acommunication filter according to an example of the present invention:

SPECIFICATIONS Electrical Specifications^([1]), Z₀ = 50 Ω, T_(C) ^([2])−20° C. to +85° C., unless otherwise specified Symbol Parameter UnitsMin. Typ.^([3]) Max. S21 Insertion Loss, Band 41 dB 2496-2500 MHz (+25°C.) 2.8 2496-2500 MHz (−20° C. to −5° C.) 3.9 2496-2500 MHz (−5° C. to+85° C.) 3.7 2500-2520 MHz (+25° C.) 2.4 3.3 2500-2520 MHz (−20° C. to+85° C.) 3.8 2520-2680 MHz (+25° C.) 2.0 3.0 2520-2680 MHz (−20° C. to+85° C.) 3.2 2680-2690 MHz (+25° C.) 2.2 3.6 2680-2690 MHz (−20° C. to+85° C.) 3.8 S21 Attenuation, 0-699 MHz dB 35 76 S21 Attenuation,699-916 MHz dB 35 56 S21 Attenuation, 916-1348 MHz dB 25 47 S21Attenuation, 1248-1565 MHz dB 25 35 S21 Attenuation, 1565-1615 MHz dB 3040 S21 Attenuation, 1615-1660 MHz dB 25 34 S21 Attenuation, 1660-1750MHz dB 18 27 S21 Attenuation, 1750-2400 MHz dB 12 22 S21 Attenuation,Wi-Fi 802.11 b/g/n Band^([4]) dB 2401-2453 MHz (Wi-Fi Ch 1-7) 35 452436-2468 MHz (Wi-Fi Ch 8-10) 35 44 2451-2473 MHz (Wi-Fi Ch 11) 30 442456-2478 MHz (Wi-Fi Ch 12) — 30 2461-2483 MHz (Wi-Fi Ch 13) — 18 S21Attenuation, 2750-2850 MHz dB 20 37 S21 Attenuation, 2850-3000 MHz dB 1828 S21 Attenuation, 3000-4992 MHz dB 20 27 S21 Attenuation, 4992-5380MHz dB 24 32 S21 Attenuation, 5380-7488 MHz dB 20 32 S21 Attenuation,7488-8070 MHz dB 20 30 S11, Return Loss (SWR), 2496-2690 MHz dB 8 16(1.4) (2.3) S22 Notes: ^([1])Min./Max. specifications are guaranteed atthe indicated temperature, unless otherwise noted. ^([2])T_(C) is thecase temperature and is defined as the temperature of the underside ofthe filter where it makes contact with the circuit board. ^([3])Typicaldata is the average value (arithmetic mean) of the parameter over theindicated band at +25° C. ^([4])Wi-Fi Channel Average Attenuation, whichis obtained by averaging [S21] over the center 19 MHz of the channelsand converting to dB value.

The following table provides the absolute maximum ratings for acommunication filter according to an example of the present invention:

ABSOLUTE MAXIMUM RATINGS^([1]) Parameter Unit Value Storage temperature° C. −40 to +125 Maximum RF Input Power to Pin 1 (Tx)^([2]) dBm +31Maximum DC Voltage, any Pin to Gnd or V_(DC) 0 between Pins^([3]) Notes:^([1])Operation in excess of any one of these conditions may result inpermanent damage to the device. ^([2])The ACPF-7141 is not symmetrical.Pin 1 is designed for higher power handling and is intended to beconnected to the Tx blocks with Pin 2 connected to the system antenna.^([3])Internal DC resistance of any port to ground or between ports isapproximately a short circuit.

The following table provides the maximum recommended operatingconditions for a communication filter according to an example of thepresent invention:

MAXIMUM RECOMMENDED OPERATING CONDITIONS^([4]) Parameter Unit ValueOperating temperature, T_(C) ^([5]) ° C. −30 to +85 Notes: ^([4])Thedevice will function over the recommended range without degradation inreliability or permanent change in performance, but is not guaranteed tomeet electrical specifications. ^([5])T_(C) is defined as casetemperature, the temperature of the underside of the filter where itmakes contact with the circuit board.

One or more benefits are achieved over pre-existing techniques using theinvention. In particular, the present device can be manufactured in arelatively simple and cost effective manner while using conventionalmaterials and/or methods according to one of ordinary skill in the art.Using the present method, one can create a reliable single crystal basedacoustic filter or resonator using multiple ways of three-dimensionalstacking through a wafer level process. Such single crystal acousticresonators enable high bandwidth-low loss filters in a miniature formfactor, and such filters or resonators can be implemented in an RFfilter device, an RF filter system, or the like. In an example, thiscommunication filter can be a miniature filter configured for use in a2496-2690 MHz wireless frequency spectrum. This filter can operateconcurrently with adjacent 2.4 GHz bands including Wi-Fi, WLAN,Bluetooth, ISM, and the like. Depending upon the embodiment, one or moreof these benefits may be achieved.

While the above is a full description of the specific embodiments,various modifications, alternative constructions and equivalents may beused. As an example, the packaged device can include any combination ofelements described above, as well as outside of the presentspecification. As used herein, the term “substrate” can mean the bulksubstrate or can include overlying growth structures such as analuminum, gallium, or ternary compound of aluminum and gallium andnitrogen containing epitaxial region, or functional regions,combinations, and the like. Therefore, the above description andillustrations should not be taken as limiting the scope of the presentinvention which is defined by the appended claims.

What is claimed is:
 1. A communication filter device comprising: apiezoelectric substrate having a substrate surface region, thepiezoelectric substrate having a piezoelectric layer formed overlying atransfer substrate; a topside metal electrode formed overlying a portionof the substrate surface region; a topside micro-trench formed within aportion of the piezoelectric layer; one or more bond pads formedoverlying one or more portions of the piezoelectric layer; a topsidemetal having a topside metal plug formed within the topside micro-trenchand electrically coupled to at least one of the bond pads; a firstbackside cavity formed adjacent to the transfer substrate and underlyingthe topside metal electrode; a second backside cavity formed within thetransfer substrate and underlying the topside micro-trench; a backsidemetal electrode formed underlying one or more portions of the transfersubstrate, within the first backside cavity, and underlying the topsidemetal electrode; a backside metal plug formed underlying one or moreportions of the transfer substrate, within the second backside cavity,and underlying the topside micro-trench, the backside metal plug beingelectrically coupled to the topside metal plug and the backside metalelectrode, wherein the topside micro-trench, the topside metal plug, thesecond backside cavity, and the backside metal plug form a micro-via; atop cap structure bonded to the piezoelectric substrate, the top capstructure including one or more thru via structures electrically coupledto one or more top bond pads and one or more bottom bond pads; whereinthe one or more bottom bond pads are electrically coupled to the one ormore bond pads and the topside metal; a backside cap structure bonded tothe transfer substrate, the backside cap structure underlying the firstand second backside cavities; and one or more solder balls formedoverlying the one or more top bond pads; wherein the top cap structureincludes a silicon substrate and wherein the one or more thru viastructures comprise thru silicon via structures electrically coupled tothe one or more top bond pads and the one or more bottom bond pads. 2.The device of claim 1 wherein the transfer substrate includes silicon,silicon carbide, aluminum oxide, silicon-on-insulation (SOI), or singlecrystal aluminum gallium nitride materials.
 3. The device of claim 1wherein the topside and backside metal electrodes include molybdenum,aluminum, ruthenium, or titanium materials, or combinations thereof; andwherein the topside metal, the topside metal plug, and the backsidemetal plug includes gold, aluminum, copper, or other interconnectmaterials.
 4. A communication filter device comprising: a piezoelectricsubstrate having a substrate surface region, the piezoelectric substratehaving a piezoelectric layer formed overlying a transfer substrate; atopside metal electrode formed overlying a portion of the substratesurface region; a topside micro-trench formed within a portion of thepiezoelectric layer; one or more bond pads formed overlying one or moreportions of the piezoelectric layer; a topside metal having a topsidemetal plug formed within the topside micro-trench and electricallycoupled to at least one of the bond pads; a first backside cavity formedadjacent to the transfer substrate and underlying the topside metalelectrode; a second backside cavity formed within the transfer substrateand underlying the topside micro-trench; a backside metal electrodeformed underlying one or more portions of the transfer substrate, withinthe first backside cavity, and underlying the topside metal electrode; abackside metal plug formed underlying one or more portions of thetransfer substrate, within the second backside cavity, and underlyingthe topside micro-trench, the backside metal plug being electricallycoupled to the topside metal plug and the backside metal electrode,wherein the topside micro-trench, the topside metal plug, the secondbackside cavity, and the backside metal plug form a micro-via; a top capstructure bonded to the piezoelectric substrate, the top cap structureincluding one or more thru via structures electrically coupled to one ormore top bond pads and one or more bottom bond pads; wherein the one ormore bottom bond pads are electrically coupled to the one or more bondpads and the topside metal; a backside cap structure bonded to thetransfer substrate, the backside cap structure underlying the first andsecond backside cavities; and one or more solder balls formed overlyingthe one or more top bond pads; wherein the top cap structure includes ametallized laminate substrate wherein the one or more thru viastructures comprise one or more thru substrate via (TSV) structureselectrically coupled to the one or more top bond pads and the one ormore bottom pads.
 5. The device of claim 4 wherein the backside capstructure includes a transfer substrate, a glass substrate, a siliconsubstrate, a sapphire (Al₂O₃) substrate, or an interposer substrate. 6.The device of claim 4 wherein the first backside cavity has a trenchshape similar to a shape of the topside metal electrode; or wherein thefirst backside cavity has a trench shape similar to a shape of thebackside metal electrode.
 7. The device of claim 4 wherein the firstbackside cavity has a cavity shape different from both a shape of thetopside metal electrode and the backside metal electrode.
 8. Acommunication filter device comprising: a piezoelectric substrate havinga substrate surface region, the piezoelectric substrate having apiezoelectric layer formed overlying a transfer substrate, wherein thepiezoelectric layer is bonded to the transfer substrate using one ormore dielectric layers containing silicon nitride, silicon oxide, orother adhesion materials; a topside metal electrode formed overlying aportion of the substrate surface region; a topside micro-trench formedwithin a portion of the piezoelectric layer; one or more bond pads moreportions of the piezoelectric layer; a topside metal having a topsidemetal plug formed within the topside micro-trench and electricallycoupled to at least one of the bond pads; a first backside cavity formedadjacent to the transfer substrate and underlying the topside metalelectrode; a second backside cavity formed within the transfer substrateand underlying the topside micro-trench; a backside metal electrodeformed underlying one or more portions of the transfer substrate, withinthe first backside cavity, and underlying the topside metal electrode;and a backside metal plug formed underlying one or more portions of thetransfer substrate, within the second backside cavity, and underlyingthe topside micro-trench, the backside metal plug being electricallycoupled to the topside metal plug and the backside metal electrode,wherein the topside micro-trench, the topside metal plug, the secondbackside cavity, and the backside metal plug form a micro-via.
 9. Acommunication filter device comprising: a piezoelectric substrate havinga substrate surface region, the piezoelectric substrate having apiezoelectric layer formed overlying a transfer substrate, wherein thepiezoelectric layer is bonded to the transfer substrate using one ormore dielectric layers containing silicon nitride, silicon oxide, orother adhesion materials; a topside metal electrode formed overlying aportion of the substrate surface region; a topside micro-trench formedwithin a portion of the piezoelectric layer; one or more bond padsformed overlying one or more portions of the piezoelectric layer; atopside metal having a topside metal plug formed within the topsidemicro-trench and electrically coupled to at least one of the bond pads;a thinned top cap structure bonded to the piezoelectric substrate, thethinned top cap structure including one or more blind via structureselectrically coupled to one or more bottom bond pads, wherein the one ormore blind via structures are exposed; wherein the one or more bottombond pads are electrically coupled to the one or more bond pads and thetopside metal; a first backside cavity formed within the transfersubstrate and underlying the topside metal electrode; a second backsidecavity formed within the transfer substrate and underlying the topsidemicro-trench; a backside metal electrode formed underlying one or moreportions of the transfer substrate, within the first backside cavity,and underlying the topside metal electrode; a backside metal plug formedunderlying one or more portions of the transfer substrate, within thesecond backside cavity, and underlying the topside micro-trench, thebackside metal plug being electrically coupled to the topside metal plugand the backside metal electrode, wherein the topside micro-trench, thetopside metal plug, the second backside cavity, and the backside metalplug form a micro-via; a backside cap structure bonded to the transfersubstrate, the backside cap structure underlying the first and secondbackside cavities; one or more top bond pads formed overlying andelectrically coupled to the one or more blind vias; and one or moresolder balls formed overlying the one or more top bond pads.
 10. Thedevice of claim 9 wherein the transfer substrate includes silicon,silicon carbide, aluminum oxide, silicon-on-insulator (SOI), or singlecrystal aluminum gallium nitride materials.
 11. The device of claim 9wherein the topside and backside metal electrodes include molybdenum,aluminum, ruthenium, or titanium materials, or combinations thereof; andwherein the topside metal, the topside metal plug, and the backsidemetal plug include gold, aluminum, copper, or other interconnectmaterials.
 12. The device of claim 9 wherein the backside cap structureincludes a transfer substrate, a glass substrate, a silicon substrate, asapphire (Al₂O₃) substrate, or an interposer substrate.
 13. The deviceof claim 9 wherein the top cap structure includes an interposersubstrate and wherein the one or more blind via structures comprise oneor more blind metal via structures electrically coupled to the one ormore bottom bond pads.
 14. A communication filter device comprising: apiezoelectric substrate having a substrate surface region, thepiezoelectric substrate having a piezoelectric layer formed overlying atransfer substrate; a topside metal electrode formed overlying a portionof the substrate surface region; a topside micro-trench formed within aportion of the piezoelectric layer; one or more bond pads formedoverlying one or more portions of the piezoelectric layer; a topsidemetal having a topside metal plug formed within the topside micro-trenchand electrically coupled to at least one of the bond pads; a thinned topcap structure bonded to the piezoelectric substrate, the thinned top capstructure including one or more blind via structures electricallycoupled to one or more bottom bond pads, wherein the one or more blindvia structures are exposed; wherein the one or more bottom bond pads areelectrically coupled to the one or more bond pads and the topside metal;a first backside cavity formed within the transfer substrate andunderlying the topside metal electrode; a second backside cavity formedwithin the transfer substrate and underlying the topside micro-trench; abackside metal electrode formed underlying one or more portions of thetransfer substrate, within the first backside cavity, and underlying thetopside metal electrode; a backside metal plug formed underlying one ormore portions of the transfer substrate, within the second backsidecavity, and underlying the topside micro-trench, the backside metal plugbeing electrically coupled to the topside metal plug and the backsidemetal electrode, wherein the topside micro-trench, the topside metalplug, the second backside cavity, and the backside metal plug form amicro-via; a backside cap structure bonded to the transfer substrate,the backside cap structure underlying the first and second backsidecavities; one or more top bond pads formed overlying and electricallycoupled to the one or more blind vias; and one or more solder ballsformed overlying the one or more top bond pads; wherein the top capstructure includes a silicon substrate and wherein the one or more blindvia structures comprise blind silicon via structures electricallycoupled to the one or more bottom bond pads.
 15. A communication filterdevice comprising: a piezoelectric substrate having a substrate surfaceregion, the piezoelectric substrate having a piezoelectric layer formedoverlying a transfer substrate; a topside metal electrode formedoverlying a portion of the substrate surface region; a topsidemicro-trench formed within a portion of the piezoelectric layer; one ormore bond pads formed overlying one or more portions of thepiezoelectric layer; a topside metal having a topside metal plug formedwithin the topside micro-trench and electrically coupled to at least oneof the bond pads; a thinned top cap structure bonded to thepiezoelectric substrate, the thinned top cap structure including one ormore blind via structures electrically coupled to one or more bottombond pads, wherein the one or more blind via structures are exposed;wherein the one or more bottom bond pads are electrically coupled to theone or more bond pads and the topside metal; a first backside cavityformed within the transfer substrate and underlying the topside metalelectrode; a second backside cavity formed within the transfer substrateand underlying the topside micro-trench; a backside metal electrodeformed underlying one or more portions of the transfer substrate, withinthe first backside cavity, and underlying the topside metal electrode; abackside metal plug formed underlying one or more portions of thetransfer substrate, within the second backside cavity, and underlyingthe topside micro-trench, the backside metal plug being electricallycoupled to the topside metal plug and the backside metal electrode,wherein the topside micro-trench, the topside metal plug, the secondbackside cavity, and the backside metal plug form a micro-via; abackside cap structure bonded to the transfer substrate, the backsidecap structure underlying the first and second backside cavities; one ormore top bond pads formed overlying and electrically coupled to the oneor more blind vias; and one or more solder balls formed overlying theone or more top bond pads; wherein the top cap structure includes ametallized laminate substrate wherein the one or more blind viastructures comprise one or more blind substrate via structureselectrically coupled to the one or more bottom pads.
 16. A communicationfilter device comprising: a piezoelectric substrate having a substratesurface region, the piezoelectric substrate having a piezoelectric layerformed overlying a transfer substrate, wherein the piezoelectric layeris bonded to the transfer substrate using one or more dielectric layerscontaining silicon nitride, silicon oxide, or other adhesion materials;a topside metal electrode formed overlying a portion of the substratesurface region; a topside micro-trench formed within a portion of thepiezoelectric layer; one or more bond pads formed overlying one or moreportions of the piezoelectric layer; a topside metal having a topsidemetal plug formed within the topside micro-trench and electricallycoupled to at least one of the bond pads; a top cap structure bonded tothe piezoelectric substrate, the top cap structure including a substratewith one or more bottom bond pads; wherein the one or more bottom bondpads are electrically coupled to the one or more bond pads and thetopside metal; a first backside cavity formed within the transfersubstrate and underlying the topside metal electrode; a second backsidecavity formed within the transfer substrate and underlying the topsidemicro-trench; a backside metal electrode formed underlying one or moreportions of the transfer substrate, within the first backside cavity,and underlying the topside metal electrode; a backside metal plug formedunderlying one or more portions of the transfer substrate, within thesecond backside cavity, and underlying the topside micro-trench, thebottom topside metal plug being electrically coupled to the topsidemetal plug, wherein the topside micro-trench, the topside metal plug,the second backside cavity, and the backside metal plug form amicro-via; a backside cap structure bonded to the transfer substrate,the backside cap structure underlying the first and second backsidecavity; one or more backside bond pads formed within one or moreportions of the backside cap structure, the one or more of the backsidebond pads being electrically coupled to the backside metal plug; and oneor more solder balls formed underlying the one or more backside bondpads.
 17. The device of claim 16 wherein the transfer substrate includessilicon, silicon carbide, aluminum oxide, silicon-on-insulation (SOI),or single crystal aluminum gallium nitride materials.
 18. The device ofclaim 16 wherein the topside and backside metal electrodes includemolybdenum, aluminum, ruthenium, or titanium materials, or combinationsthereof; and wherein the topside metal, the topside metal plug, and thebackside metal plug include gold, aluminum, copper, or otherinterconnect materials.
 19. The device of claim 16 wherein the backsidecap structure includes a silicon substrate, a glass substrate, a siliconsubstrate, a sapphire (Al₂O₃) substrate, or a smart-glass substrate. 20.A communication filter device comprising: a piezoelectric substratehaving a substrate surface region, the piezo electric substrate having apiezoelectric layer formed overlying a transfer substrate, wherein thepiezoelectric layer is bonded to the transfer substrate using one ormore dielectric layers containing silicon nitride, silicon oxide, orother adhesion materials; a topside metal electrode formed overlying aportion of the substrate surface region; a topside micro-trench formedwithin a portion of the piezoelectric layer; one or more bond padsformed overlying one or more portions of the piezoelectric layer; atopside metal having a topside metal plug formed within the topsidemicro-trench and electrically coupled to at least one of the bond pads;a shared backside cavity formed within the transfer substrate andunderlying the topside metal electrode and the topside micro-trench; abackside metal electrode formed underlying one or more portions of thetransfer substrate, within the shared backside cavity, and underlyingthe topside metal electrode; and a backside metal formed underlying oneor more portions of the transfer substrate, within the shared backsidecavity, and underlying the topside micro-trench, the backside metalbeing electrically coupled to the topside metal plug and the backsidemetal electrode, wherein the topside micro-trench, the topside metalplug, and the backside metal form a micro-via.
 21. The device of claim20 wherein the transfer substrate includes silicon, silicon carbide,aluminum oxide, silicon-on-insulation (SOI), or single crystal aluminumgallium nitride materials.
 22. The device of claim 20 wherein thetopside and backside metal electrodes include molybdenum, aluminum,ruthenium, or titanium materials, or combinations thereof; and whereinthe topside metal, the topside metal plug, and the backside metalincludes gold, aluminum, copper, or other interconnect materials. 23.The device of claim 20 further comprising a backside cap structurebonded to the transfer substrate, the backside cap structure underlyingthe shared backside cavity, wherein the backside cap structure includesa transfer substrate, a glass substrate, or an interposer substrate. 24.The device of claim 20 wherein the backside metal electrode is patternedwithin the boundaries of the shared backside cavity such that thebackside metal electrode does not come in contact with one or moreside-walls of the transfer substrate created during the forming of theshared backside cavity.